The numbers behind the implementation of the EU-Turkey migration deal

The European Union is working on implementing a challenging new migration deal with Turkey that is mean to stem the flow of migrants trying to reach European shores.

Here are some key numbers.

72,000: The maximum number of Syrian asylum seekers that the EU will return from Greece to Turkey in a bid to undercut migrant smuggling networks in the Aegean Sea. Under the deal with Ankara, the exact same number of Syrian asylum seekers will be resettled from Turkey to the EU. The scheme is expected to start operating by early April.

20,000: The short-term accommodation spots needed on the Greek islands to host asylum seekers while they are processed. Only 6,000 exist so far, according to the European Commission, the EU's executive.

4,000: The staff members that Greece will need to implement the EU-Turkey deal, according to commission estimates. They include asylum experts, judges, interpreters, police officers and security staff. The commission says around 1,500 of those people are already present in Greece; it hopes that the rest will be provided by other EU member states. First deployments are expected on March 28.

190: The number of containers that the commission estimates will be needed to house administrators, including 130 for case workers from the European Asylum Support Office.

28 and 8: The number of buses and vessels, respectively, that will be needed to help transport asylum seekers from Greece to Turkey, the commission estimates. Ferry boats would be the fastest way to return them; discussions are ongoing with private market firms to see if they can contribute, an EU source said on condition of anonymity.

20: The number of EU countries that have submitted confirmed offers to help in Greece, notably with asylum experts, return and readmission experts, and police officers, according to commission spokesman Margaritis Schinas. They are Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Italy, Lithuania, Luxembourg, the Netherlands, Poland, Portugal, Romania, Slovenia, Slovakia and Spain. "All other member states showed willingness to pledge," Schinas said. Germany and France have each promised to provide 300 asylum experts and police officers.

280 million euros (315 million dollars): The estimated cost for the scheme of accelerated returns and readmission to Turkey for the next six months, according to an EU source. The money will come out of the EU's budget.

Beirut (dpa) - Syrian government forces and their allies advanced deeper into the shrinking rebel-held enclave in eastern Aleppo on Wednesday, seizing the Old City, while demanding the armed opposition groups leave the area.